This invention relates to measuring or the like. In the past it has been known to measure various parameters by measuring an oscillator frequency which is responsive to the parameter under test or to be measured. The change in frequency as a result of a change in the parameter could be measured or counted, and the value of the change in the parameter could be deduced. One way of making the measurement was to use a pair of oscillators. One oscillator is usually a "reference" or standard; i.e., a crystal controlled precision oscillator. The oscillators were synchronized by known techniques so as to stabilize one oscillator relative to the other by developing an analog voltage representing the required correction, and applying it to one of the oscillators, usually the non-standard, which would be responsive to such a voltage in order to bring the two oscillators into synchronism. Accordingly the one oscillator would be stabilized relative to the other. Consequently when, after synchronization, the oscillators were dissociated, there was a change in the frequency of one of those oscillators caused by a change in the parameter to be measured, the difference in frequency between the two oscillators could be measured or counted, by measuring the frequency of one against the other, to give the change in the parameter under test. Various other devices are known for synchronizing two such oscillators or stabilizing an oscillator and then measuring or counting the change in the frequency caused by a change in the parameter under test. There are known various systems for controlling frequency, such as represented by voltage-controlled oscillators, variable reactances and the like. The following patents may be considered as representative:
U.S. Pat. Nos. 3,761,810 to Fathauer, Sept. 25, 1973; U.S. Pat. 3,794,911 to Fathauer, Feb. 26, 1974; U.S. Pat. 3,888,473 to Heyck, May 27, 1975; U.S. Pat. 3,967,690 to Northcutt, July 6, 1976; U.S. Pat. 3,893,040 to Harp, July 1, 1975; U.S. Pat. 3,488,605 to Schwartz, Jan. 6, 1970; and U.S. Pat. 3,370,252 to Zoerner, Feb. 20, 1968. Also of interest are the following patents: U.S. Pat. Nos. 3,227,952 to Proebster et al, Jan. 4, 1966; U.S. Pat. 3,370,252 to Zoerner, Feb. 20, 1968; U.S. Pat. 3,392,348 to Horwitz, July 9, 1968; U.S. Pat. 3,484,712 to Foote et al, Dec. 26, 1969; and U.S. Pat. 3,875,525 to Ballinger et al, April 1, 1975; and also German Pat. No. 2,333,196 to Ise Electronics Corporation of Japan laid open on Jan. 24, 1974, which shows a digital bathroom scale which may be of some interest here because the present application illustrates the invention herein as related to a weighing device.